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Joining and Surface Modification of Age-Hardening Alloys through Laser Processing

通过激光加工连接和表面改性时效硬化合金

基本信息

批准号：
09650787
负责人：
HIROSE Akio
金额：
$ 2.11万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650787/
关键词：
Laser processing Laser beam welding Age hardening alloys Joining Surface modification Aluminum alloy Ni base super alloy Kinetic equation

项目摘要

In the present research, laser processes have been applied to joining and surface modification of age-hardening alloys and their beneficial characteristics have been developed.In the laser beam welding of age hardening 6061-T6 aluminum alloy and Ni base super alloy, Inconel 718, the widths of softened regions were extremely narrower than those of tungsten inert gas (TIG) welds.The softening comes from the dissolution of age precipitates, beta" in 6061-T6, and gamma' and gamma"in Inconel 718, by a weld heat input.Thus, a low overall heat input of laser beam welding can minimize the softened regions.The laser beam weld joints had higher strengths than those of TIG weld joints after post-weld aging heat treatments for both alloys.This advantageous characteristic of laser beam welding was quantitatively evaluated through predicting hardness distributions in weld heat affected zones using a newly developed kinetic equation describing the dissolution of age precipitates.Prediction of the width of softened regions with varying power inputs and welding speeds reveals that a high energy density and a high welding speed in laser beam welding results in significantly narrower softened regions, in which the width is insensitive to variations in welding parameters compared to that of TIG welding.Laser processing was also applied to surface modification of Inconel 718 for reducing sensitivity to hydrogen embrittlement of the alloy.Scanning laser beam on to the surface of Inconel 718 could locally produce surface solutionized zones.The surface solutionized zones were softened by the dissolution of age precipitates.This laser surface solutionizing is effective in preventing hydrogen cracking of Inconel 718 with little sacrifice of the strength of structures.The ductility of the surface solutionized specimen was almost twice that of the base metal in a tensile test under a 29.4MPa hydrogen atmosphere at room temperature with hydrogen pre-charging.

在目前的研究中，激光工艺已应用于时效硬化合金的连接和表面改性，并开发了其有益的特性。在时效硬化6061-T6铝合金和Ni基高温合金Inconel 718的激光焊接中，软化区宽度比钨惰性气体（TIG）焊缝的宽度窄得多。在焊接热输入的作用下，时效析出物（6061-T6中的β “和Inconel 718中的γ '和γ ”）被溶解。因此，低总热输入的激光束焊接可以减少软化区。两种合金经焊后时效热处理后，激光束焊接接头的强度均高于TIG焊接接头。通过使用新开发的描述时效析出物溶解的动力学方程预测焊缝热影响区的硬度分布，定量评价了激光焊接的这一优势特性。对不同功率输入和焊接速度下的软化区宽度的预测表明，与TIG焊接相比，高能量密度和高焊接速度的激光束焊接软化区明显变窄，且软化区宽度对焊接参数的变化不敏感。为了降低合金对氢脆的敏感性，还采用激光处理技术对Inconel 718进行了表面改性。扫描激光束照射到Inconel 718表面，可产生局部固溶区。年龄相的溶解使表面溶化带软化。激光表面固溶能有效地防止Inconel 718的氢裂，且组织强度损失小。在29.4MPa室温氢气气氛下预充氢拉伸试验中，表面固溶试样的延展性几乎是母材的两倍。